Yes, you can redirect STDOUT to a variable. But you need some kind of statement to select between "normal STDOUT" and the "variable STDOUT". Another possibility is open a filehandle to a variable and just add that filehandle after the print's that you want to go there. And then just print that variable when you want that output to show up? Note: all I/O routines return status, including print - that's what causes this extra '1' to show up in the printout and it is the default return value from sample(), assuming the print succeeds which it almost always does.

I guess there are some other possibilities here, depending upon whether you are writing to a file or to something that Perl can identify as the console. STDERR is non-buffered while STDOUT is buffered when writing to pipes,files. STDERR will come out right NOW, vs STDOUT which will print when it's buffer is full, maybe 4-8K bytes or so.

#!/usr/bin/perl -w
use strict;
use 5.10.0;  ## needed for "say"

print "First, Order as written:\n";
my $str  = q[new text];
$str .= sample( qw(1 2 3) ); #adds '1' to $str
$str .= q[more new text]; 

print_now( "$str \n" ); 

sub sample {
    print q[sample(): ], @_, "\n"; 
}

sub print_now {
    say @_;   ## or
   # print $FH @_;  # this an error what is $FH?
}

print "Now, reverse order:\n";
####################

my $delayedout;
open (DELAY, '>', \$delayedout) or die "$!";
$str  = q[new text];
$str .= sampleb( qw(1 2 3) ); 
$str .= q[more new text]; 

print_nowb( "$str \n" ); 
print $delayedout; 

sub sampleb {
    print DELAY q[sample(): ], @_, "\n"; 
}

sub print_nowb {
    say @_;       
}
__END__
PRINTS:
First, Order as written:
sample(): 123
new text1more new text # 1 is return value of sample
                       # extra \n comes from say statement.
Now, reverse order:
new text1more new text 

sample(): 123
[download]